On Fri, 26 Dec 2003 19:00:45 -0800, Andrew Morton wrote:> The current behaviour seems better from a theoretical point of view. All> we want to know is the reference pattern - whether it is one process> referencing the page frequently or 100 processes referencing it> infrequently shouldn't matter. And if we want to give mapped pages more

It can matter. Evicting a page that is infrequently referenced by manyprocesses increases the chance that all runnable processes block waitingfor that same page later. The likelihood of that happening grows undermemory pressure, when "infrequently" may actually be "quite often" andwhen disk I/O is congested (resulting in higher disk access times).

You won't have the same effect when evicting a page that is referencedby one process only, no matter how frequently.

Having all processes blocked is indeed one problem of 2.6 under memorypressure. I don't know what the cause is, though.